Our cook had the anaconda by the throat. I'll just repeat that. Our cook had the anaconda by the throat. The anaconda, as long as a bus, had burst out of the water and grabbed the piranha from the cook's hands as he cleaned it at the riverbank. The anaconda wanted an easy meal. Our cook wanted to make sushi, with a ginger jus. Neither wanted to give in.

They wrestled, eye to eye, the anaconda's brown and yellow body, as thick as the cook's thigh, stretching down into the water. Finally, the anaconda broke the clinch and fell back into the river - with our fish supper.

And what was I doing? Put it this way, I wasn't at the front of the queue rushing to the cook's aid. Anaconda? Piranha? What sort of B-movie was this? Jungle III: the Critters' Revenge would see me the first to die, ambushed and gummed to death by a giant equatorial slug.

That's the thing about the Pantanal in southern Brazil. There's a hell of a lot of wildlife about. So I was a little uneasy when, a few days after this incident, I learnt that another anaconda lived in the lake just a few seconds' slither from the front door of my room at the Araras Eco Lodge. 'It's only a baby - just a metre or two,' said one of the guides. Hmm...

The lodge sits in the heart of the Pantanal, the world's largest freshwater wetland system, supporting an extraordinary diversity of wildlife - 698 bird species, 80 mammals, 260 fish species and 50 types of reptile.

Each winter, with the rains, land becomes water for a few months. The water retreats during the spring, leaving fertile savannah and ponds full of fish which didn't manage to get back to the rivers as the land dried - ready meals for the predators.

And, unlike in the Amazon, you can actually see the wildlife - the Amazon's dense, thick forest hides its secrets well, but the Pantanal's savannah and relatively clear woodland put the wildlife on open display for the rather lazy visitor.

On my first afternoon at the lodge, Noah, my guide, led me on a walk through its extensive lands. Howler monkeys gossiped about us from the trees, and toucans flew by, their giant beaks defying the laws of aerodynamics. Bright blue hyacinth macaws clung on to palm trees, delicately nibbling at the fruit.

The Big Bird of the Pantanal is the jabiru stork, as tall as a Mini, which stood decorously by ponds before skewering unfortunate fish. The title for the noisiest bird goes to the aracua - they sat in pairs in trees shouting 'Ka-ka-kow' at each other. Such a common sound had to have some local meaning. 'Yes,' Noah explained with a laugh, 'the female's saying "Quero casar" [Let's get married] and the male retorts "Quero largar" [Let's break up].'

Then, by the water's edge, there were two capybara, like giant guinea pigs bred by a crazed Kent pet shop owner. These rodents looked at us with the glazed expression of an animal indifferent to predators, or perhaps like an animal that is just very, very stupid.

Pretty birds, comic monkeys - I was in Disney World. Ah, lovely... then we went round a corner and reality bit.

An eight-foot-long caiman (Pantanal alligator) blocked the narrow path ahead. We looked at it. It looked at us. I looked at Noah. He looked puzzled, then surveyed the scrub and armed himself with a twig. Not a branch, an eight-inch twig. He waved it at the caiman and it just glowered at him. He jabbed at its unblinking eye. Finally, he gave it a whack with the twig - the caiman merely hissed. Just when I thought Noah was going to make me step over its jaws, the caiman lumbered off, point made.

Next day, a truck took us to a river marking the edge of the lodge's lands. Piranha fishing was promised, but first I climbed into a kayak and paddled unsteadily away in a life jacket that made me feel like the meat in an anaconda sandwich.

I peered suspiciously at every swirl in the impenetrable brown water before cries from round a bend in the river had me paddling faster, just in time to spot a tapir, its lugubrious face and long nose making it look nothing so much as an amphibious Clement Freud, swimming across the river and climbing delicately out at the opposite bank.

It disappeared into the bush, but before I had time to be disappointed by this fleeting glimpse of such an extraordinary animal, a coughing sound ahead had me paddling off again. A family of giant river otters, the size of Labradors, appeared, barking at us indignantly from among tangles of tree roots in the water. I would have got closer but they didn't seem terribly welcoming - and neither was the smell from their larder, a stash of half-eaten, rotting fish.

It proved a lucky day for the piranhas as a massive rainstorm forced us to skid back in the truck to the lodge as the earth disappeared yet again under the water.

The Pantanal's vast plains are prime cattle country, feeding Brazilians' insatiable appetite for beef. Araras has its own herd and its own cowboys. Our guide, Edisinho, saddled each of us up on a Pantaneiro, the horses of the estancias, small and light enough to pick their way through the wetland without sinking.

Grinning, Edisinho explained how an anaconda had eaten a fisherman near here. The snake was hunted down and the fisherman's body pulled from its belly. I think I preferred it when he was telling me 101 uses for the fruit of the palm tree. The oil can treat eye complaints, apparently...

My last night was to be spent in a camp a couple of hours by horse from the lodge. Obviously, we would need something for dinner, so we were soon back in those kayaks dangling hooks off the sides.

Piranhas proved hungry, but cunning, prey. Time after time, I pulled up an empty hook. Finally, one must have been nominated by the rest to sacrifice itself for the greater tourist good and I had my four-inch prize, looking at me with a toothy grin. Edisinho put a bamboo shoot in its mouth which it snapped in two with one bite. Within a couple of hours we had a skewerful, enough for our starter.

Our cook served up a plate of fried piranha. She crunched into one, biting off the head, chewed it down, smiling mischievously at me, then spat out the pearly-white, dagger-sharp teeth one by one. 'It's the only part of the fish you can't eat,' she said, smacking her lips.

A bottle of cachaca, Brazilian rum, was downed by the light of the fire before I fell asleep to the sound of crackling logs and the furtive snuffling of a couple of foxes ripping crabs apart.

We got back to the lodge in the morning and I finally fell victim to the Pantanal's wildlife - in the shower. Attacked, I'm ashamed to say, not by an anaconda but by two blood-filled ticks which I found latched on to my bum.

Essentials

Three nights at the Pousada Araras Eco Lodge starts at £407pp, (flights not included) with Sunvil (020 8568 4499; sunvil.co.uk). Its 12-night 'Essential Brazil' tour costs from £2,452pp, including flights, three nights in Rio, three in the Pantanal, two in historic Salvador and four at the beach at Praia do Forte.